In the 3rd Generation Partner Project (3GPP) Long Term Evolution (LTE) system, a base station (also referred to as a NodeB or an evolved NodeB (eNB)) transmits scheduling information (for example, Uplink (UL) grant) on a Physical Downlink Control Channel (PDCCH)/enhanced Physical Downlink Control Channel (ePDCCH). A User Equipment (UE) reads the scheduling information on the PDCCH/ePDCCH, and transmits uplink data in uplink subframes indicated by the scheduling information. Here, the UE may be a user terminal, a user node, a mobile terminal, or a tablet computer.
The scheduling timing is specified in 3GPP LTE Release 10. Here, the scheduling timing specifies a correspondence between the downlink subframes for transmitting scheduling information and uplink subframes scheduled by the scheduling information.
A problem that may exist in LTE Release 12 is presented in the document “R1-125117, 3GPP TSG RAN VVG1 Meeting #71, Qualcomm Inc.”. A New Carrier Type (NCT) will be supported in LTE Release 12. In the NCT, the system shall continue supporting Multimedia Broadcast Multicast Service (MBMS), which will continue using the standardized configuration in LTE Release 12 and before. According to the standardized configuration in LTE Release 12 and before, radio resources for MBMS and radio resources for PDCCH are multiplexed in a time division manner in Multicast Broadcast Single Frequency Network (MBSFN) subframes. However, in LTE Release 12, in frequency bands dedicated to the NCT carrier (also referred to as “separate NCT”), the system uses ePDCCH instead of PDCCH. In this case, the radio resources for MBMS and radio resources for ePDCCH in the MBSFN subframes cannot coexist in one NOT carrier at the same time in a time division multiplexed manner. Therefore, in order to enable the MBMS in the NCT in a Time Division Duplex (TDD) mode to continue using the standardized configuration in LTE Release 12 and before, the scheduling timing of the uplink resources needs to be modified.
Therefore, there is a need for a new scheduling timing, so that, even if some downlink subframes are unavailable for transmitting scheduling information (for example, when they have been used for MBMS), the corresponding uplink subframes can still be scheduled, and the influence on the current standard can be minimized.